I’d say there’s a difference between HDR and ‘shopped, as in HDR Photoshop is used to combine data from several different exposures with real image data, rather than having the user add artificial image data afterwards. I’m sure there’s a lot of the latter in these images though, if only as local tone tweaking, but they’re still very impressive! Those ducks didn’t move around a lot during all those exposures.

That shot is taken during the day, notice the sun. I doubt that’s the moon, and that’s not a night sky with a long exposure IMO. HDR is just used to show a larger spectrum image, and that image doesn’t have to be nightime.

You take several photos, keeping the camera still but having different exposure times for each shot. Then you use a software (for example Photomatix) to combine the photos in one image, choosing the settings for optimal niceness. See for instance: http://www.popphoto.com/howto/3038/how-to-create-high-dynamic-range-images.html
You can get amazing results with quite simple settings, but this guy obviously goes over the top with his images.

HDR imaging is different from traditional photography, you can’t judge them by the same standards, as far as I’m concerned. They bring into view things the way that couldn’t be seen by naked eye, so in that respect they’re “unnatural”, but I love it nonetheless!